This invention relates to an apparatus for making investigations with microscopes. More particularly, this invention relates to a method and apparatus usable with an optical microscope for visually detecting the presence of a microscopic object in a sample and determining the position of the object in the sample to enable repeated visual observation of the object.
U.S. Pat. No. 4,833,382 to Gibbs discloses such a method and apparatus. As described in that patent, a slide holder is removably attachable to a stage of an optical microscope for shifting a slide to enable a visual inspection of a sample on the slide and a determination of the position of a microscopic object in the sample. The slide holder includes a frame stationary with respect to the stage and a slide carrier shiftable with respect to the frame. The microscope is provided with a lens system having an optical path, cooperating elements being provided on the slide and the carrier for positioning the slide at a fixed position and orientation with respect to the carrier. A zeroing or reference mark is provided on the slide for establishing an x-y coordinate system reference position of the carrier with respect to the frame, the zeroing or reference mark being integral with and essentially permanently disposed on the slide and separate from the sample and viewable by an observer through the lens system of the microscope upon a mounting of the slide to the carrier and upon an adjusting of the position thereof with respect to the microscope so that the reference mark is disposed in the optical path.
The apparatus, method and associated slide described in U.S. Pat. No. 4,833,382 has many advantages, in particular its ability to facilitate locating a microscopic object of a desired kind to enable repeated observations of the microscopic object subsequent to the initial location thereof. It has been found in practice, however, that despite the advantages, the apparatus and method give rise to certain inconveniences to users. In particular, laboratories which use the apparatus frequently receive from their customers slides which are not provided with the requisite reference mark. The slides must then be examined by ordinary techniques to relocate previously located organisms and other microscopic objects.